Hydrodynamic fluid brake



P 3, 1963 w. G. WESTWELL ETAL 3,399,747

HYDRODYNAMIC FLUID BRAKE 2 Sheets-Sheet 1 Filed May 23, 1966 I nvenlorsW/ZZ/AM 6. WFSTWHL R0651? H. 6155 d New & 921M Attorneys P 1968 w. G.WESTWELL ETAL 3,399,747

HYDRODYNAM I C FLUID BRAKE 2 Sheets-Sheet 2 Filed May 23, 1966 Invenlora m m wm m QWM W5 s United States Patent 3,399,747 HYDRODYNAMICFLUID BRAKE William G. Westwell, Peterborough, and Roger H. Slee,Surrey, England, assignors to Perkins Engines Limited, London, EnglandFiled May 23, 1966, Ser. No. 552,234 Claims priority, application GreatBritain, May 26, 1965, 22,283/ 65 2 Claims. (Cl. 18890) ABSTRACT OF THEDISCLOSURE A hydrodynamic fluid brake including a casing housing a rotorand stator. A plurality of shutter members are located between the rotorand stator. When the casing is empty of hydraulic fluid, the shuttersmay be closed to interrupt the flow of air between the rotor and stator.For braking, the shutters are opened and hydraulic fluid is introducedinto the casing. The interaction of the fluid between the rotor andstator provides a braking effect.

This invention relates to fluid machines of the type having a rotor anda stator and which, when the machine has fluid therein, can provide abraking effect by interaction of the fluid between the rotor and stator.

One example of a fluid machine of this type is a hydrodynamic fluidbrake in which the braking action is obtained by filling the casing of arotor and stator with hydraulic fluid which circulates in a vortexbetween blading or pockets on the rotor and stator. However, it is adisadvantage that when the hydraulic fluid is removed from the casing,air contained in the casing gives rise to appreciable windage losses.

It is an object of the present invention to provide means for reducingthe windage losses of fluid machines of this type.

In accordance with the present invention, a plurality of shutter membersare located between the rotor and stator. When the casing is empty ofhydraulic fluid, the shutters may be closed to interrupt the flow of airbetween the rotor and stator. For braking, the shutters are opened andhydraulic fluid is introduced into the casing. The interaction of thefluid between the rotor and stator provides a braking effect.

Preferably, the shutters are mounted on a stationary part of the machinehaving control means for Opening and closing the shutters.

The control means may include spring means for effecting movement of theshutter members to the closed position, and a hydraulic control systemfor effecting movement of the shutter members to the open position.

The shutter members may be pivotally mounted at one end on the machine,and may overlap and together form a variable aperture device or iris.

Embodiments of the invention will now be described, by way of example,with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary exploded perspective of the rotor and stator ofone embodiment of a fluid machine according to the present invention;

FIGS. 2A and 2B are front views of the stator corresponding to FIG. 1 toa reduced scale and showing the shutter members respectively in theirclosed and open positions; and

FIG. 3 is a view corresponding to FIG. 1 of a rotor and showing anotherembodiment of the invention.

Referring to FIG. 1, reference numeral designates a rotor having aplurality of rotor pockets 11B disposed on a pitch circle. Rot-or 10 isrotatably contained in one part 12B of a split casing of which the otherpart is indicated at 12A and forms the stator of the machine. The

3,399,747 Patented Sept. 3, 1968 casing part 12B has an annular land 13from which project a plurality of studs 14 which engage in a corresponding plurality of holes 14A in a corresponding land 13A on the part 12Afor fastening the casing parts together. The stator has a plurality ofpockets 11A which are axially opposite the rotor pockets 11B when theparts 12A, 12B are assembled. By virtue of the lands 13, 13A thereexists a small axial space between the rotor pockets 11B and statorpockets 11A.

Located in the space between pockets 11A- and 11B provided by lands 13,13A is means for interrupting flow of fluid between the rotor pockets11B and the stator pockets 11A. In the illustrated embodiment, thismeans consists of a plurality of shutter members 16 pivotally mounted onthe casing part 12B on a pitch circle beyond the outer diameter of therotor 10. The shutter members 16 are thin metal blades of generallyarcuate shape and overlap so as to form a variable aperture device oriris. Each member 16 has an axial pin 17. In order to pivot the shuttermembers 16, a rotatably adjustable ring 18 is provided which has slots19 in which the pins 17 are located. Each slot 19 is generally radiallydirected so that, when the ring 18 is adjusted, the shutter members 16are induced to pivot on the stationary casing 12A. The shutter members16 are movable between an open position allowing hydraulic fluid flowbetween the rotor and stator, and a closed position in which the members16 interrupt air flow between the rotor and stator. FIGS. 2A and 2B showthe shutter members 16 respectively in their closed and open positions.

Control of rotation of ring 18 is provided by a gear segment 20 attachedto the ring 18, an axially slideable rack 21 housed in the machine andmeshing with the segment 20, and control means, which may be hydraulic,pneumatic, or mechanical for example, controlling axial movement of therack 21.

Rack 21 is loaded by a compression spring 21A on an extension rod 213 ofthe rack 21 and has a control rod 21C. Extension rod 213 is connected bya coupling 21D to a hydraulic fluid control valve 22 through which fluidmay flow to fill the machine. When the rack 21 is moved in onedirection, the direction of the arrow in FIG. 1, the supply of hydraulicfluid to the machine is increased, whereas movement of the rack 21 inthe opposite direction causes less hydraulic fluid to be supplied to themachine, or the supply to be cut off.

Movement of the rack 21 in the direction of the arrow in FIG. 1 alsoeffects movement of the shutter members 16 to their closed position, andmovement of the rack 21 in the opposite direction by spring 21A elfectsopening of the shutter member 16.

When the machine contains no hydraulic fluid, and the shutter members 16are in the position in which they interrupt flow of air between therotor and stator, little or no windage effect is experienced.

In the embodiment shown in FIG. 3, there is a split casing part 46,generally similar to the casing part 12B of FIG. 1, housing a rotor 47and having an annular land 48 with studs 49. Four shutter members aregrouped in opposed pairs 50A, 50B. The shutter members 50A have a commonpivotal connection 51A with the casing part 46, and the shutter members50B have a common pivotal connection 51B with the casing part 46 whichis diametrically opposed to pivotal connections 51A. The shutter members50A, 50B of each pair extend circumferentially in opposite directionsand the adjacent free ends of the members 50A and 50B overlap. Each freeend of the shutter member has a circumferentially directed slot 52.

The shutter members 50A, 50B can be pivoted on the pivot 51A, 51Brespectively between an open position and a closed position in whichthey interrupt flow of air and hence the windage effect between therotor and. stator I 3 when the machine contains no hydraulic fluid. Themeans for effecting such movement consists of a pair of hydraulic rams53 in the casing wall for closing the members and acting on arms 54A,55A of a lever device having a pair of bellcrank levers with a commonpivot point coincident with the pivot 51B, the other arms 54, 55 of thelevers overlaying a pair of shutter members 503. At the free end of eachof the arms 54, 55 there is an axial pin 56'projec'ting into the slots52 of the overlapping shutter members 50A, 50B. A compression spring 57for effecting closing of the shutters acts on the arms 54A, 55A andurges the lever device to move the members 50A, 503 to a position inwhich the air transmission effect or windage effect is interruptedwhenever the pressure in the rams 53 is removed. I I

Rams 53 are controlled by a control valve 58 which also controls,through a hydraulic ram 58A and a valve in a casing 22A, the amount ofhydraulic fluid supplied to the machine. The control valve 58 may beoperated by known control means, for example hydraulic or pneumaticthrough a pipe 59 or by mechanical control means.

When there has to be interaction of the hydraulic fluid between therotor and stator so as to cause a braking effect on the rotor, thecontrol valve 58 is first operated so as to actuate the rams 53 and 58Ain a direction such that the shutter members 50A, 50B are held open bythe lever device, and fluid is fed into the machine via the valve in thecasing 22A.

If it is desired to remove the braking effect, the control valve 58 isactuated so that the hydraulic fluid supply is cut off and the hydraulicpressure in the rams 53 falls, and the spring 57 then acts on the arms54A, 55A so that the pins 56 move radially inwards, causing the shuttermembers 50 to close and interrupt air flow between rotor and stator.

It is not necessary that there be four shutter members, as any evennumber of such members may be used.

By pivoting the shutter members on a stationary fixture, a quick,reliable operation is obtained.

In the embodiments described, the control systems are so arranged thatthe shutter members cannot be moved to their closed position while thereis hydraulic fluid in the vortex path, and hydraulic fluid cannot beadmitted while the shutters are closed.

Modifications may be made, for example the rotor and stator could beprovided with blades,'instead of pockets.

We claim:

1. A fluid machine comprising a casing, a rotor and a stat-or receivedin the casing, reaction elements in the 0pposed faces of the rotor andstator cooperable when in fluid communication with each other togenerate fluid forces resisting rotation of the rotor relative to thestator, a plurality of shutter members mounted between the rotor andstator for selective movement between a closed position to interrupt thefluid flow between'the rotor and stator and an open position permittingfluid flow between the rotor and stator, said shutter members comprisingarcuate blades pivotally mounted at one end of the casing, control meansfor actuating said shutter members, said control means including arotatable adjusting ring connected with said shutter members operableupon rotation in opposite directions to open and close the shuttermembers, a movable control valve for controlling fluid flow to thecasing, gear means interconnecting the control valve and adjusting ringoperable to rotate the adjusting ring in opposite directions in responseto movement of the control valve in opposite directions, said gear meansincluding a rack slideably mounted on the casing, and movable inopposite directions by said control valve, and a toothed segment mountedon the adjusting ring in engagement with said rack.

2. A fluid machine as claimed in claim 1 further including a pin on eachshutter member spaced from the pivotal axis of the shutter member, and aplurality of radial slots in the adjusting ring each receiving one ofsaid pins, the engagement of said pins and slots transmitting rotationof the adjusting ring to the shutter members to cause pivotal movementof the shutter members between open and closed positions.

References Cited UNITED STATES PATENTS 1,595,657 8/1926 Halloran 2512l2XR 2,649,272 8/1953 Barbato 251--212 3,023,581 3/1962 Langlois et a1.

FOREIGN PATENTS 960,671 6/1964 Great Britain.

MILTON BUCHLER, Primary Examiner. G. E. A. HALVOSA, Assistant Examiner.I

